Sirdal is a municipality in Agder county, Norway. It is located in the northwestern part of the traditional district of Lister. The administrative centre of the municipality is the village of Tonstad. Other villages in Sirdal include Bjørnestad, Haughom, Kvæven, Lunde, and Tjørhom. The municipality is the 52nd largest by area out of the 356 municipalities in Norway. Sirdal is the 291st most populous municipality in Norway with a population of 1,810. The municipality's population density is and its population has decreased by 0.3% over the previous 10-year period. The old parish of Sirdal was first established as a municipality in 1849 when it was separated from the large municipality of Bakke. Initially, Sirdal had 1,804 residents. On 1 January 1903, a small area of Sirdal (population: 63) was transferred to the neighboring municipality of Fjotland. On 1 January 1905, the municipality of Sirdal was dissolved and its territories were divided into two new municipalities: Tonstad (population: 828) and Øvre Sirdal (population: 753). These large, sparsely populated municipalities merged along with the Øksendal area of Bakke municipality to recreate the municipality of Sirdal on 1 January 1960. This time, Sirdal started out with a population of 1,426. On 1 January 1987, the Virak and Espetveit areas of northern Flekkefjord (population: 41) were transferred to Sirdal municipality. The municipality (originally the parish) is named after the Sirdalen valley (Sírudalr) since the valley runs through the municipality. The first element is the genitive case of the river name Síra (now the Sira river). The river name has an unknown meaning, but it could be something like "strong stream". The last element is dalr which means "valley" or "dale". the name of Utsira The coat of arms was granted on 17 January 1986. The official blazon is "Vert, three ptarmigans volant argent" (I grønt tre oppflygande sølv ryper, 2 - 1). This means the arms have a green field (background) and the charge is a willow ptarmigan (Lagopus lagopus).